FR2468402A2 - AQUEOUS MICROEMULSIONS OF ORGANIC SUBSTANCES - Google Patents

Abstract

New surfactants make it possible to obtain microemulsions, even in the presence of aqueous saline solutions; these agents are N-acyl alpha-amino acid salts

Description

In the main patent, new surfactants have been described,

particularly useful for obtaining microemulsions, these agents being constituted by N-acyl α-amino acid salts of the type

R

Rt-CO-NH-CH-COOH.

  The practical results, reported in this main patent

  cipal, indicated that the weight proportions of the agents in question should be above all of the order of 5 to 30% of the mixture

  microemulsified, to ensure good stability thereof.

  The rest of the work on this subject revealed, unexpectedly, that by appropriately adapting the different factors that govern the formation of emulsions or microemulsions, it becomes possible to obtain good results with concentrations

  much lower surfactant (s). In part-

culier, with suitable salinities of water, well-chosen coagents and agents whose radical R has a mass

sufficient molecular weight, stable microemulsions can be obtained

  wheat, in particular of hydrocarbons and water, with

  agent equal to or somewhat less than 0.5%.

  The invention is characterized in that the proportion

  N-acyl a-amino acid salt surfactant is lower

  re to 5 parts and especially between approximately 0.5 and 5 parts

parts by weight per 100 parts of microemulsified mixture

preferred proportions are from 1 to 4% and - more especially -

2.5 to 3.5%.

Although it is known to employ weak concen-

trations, in particular less than 1%, of surfactant compounds, in the preparation of various emulsions, the microemulsions of

  hydrocarbons with water require very sub-

  stantiales, generally greater than 5%; there is therefore an advantage

  unexpected step in the application of the present invention.

On the other hand, both with regard to the main patent

cipal as this 1st Addition, it is surprising that the

  N-acyl α-amino acid salts according to the invention are so effective

caces for the preparation of microemulsions, while their isomers, proposed as emulsifiers in US Pat. No. 2,047,069, are not indicated for this use. These are defined by the formula

2 2468402

R-CO-N-R2COOX

  R1 o R is an alkyl having at least 7 atoms of C, R1 and R2 are hydrocarbon radicals, optionally substituted, and X a hydrogen, ammonium or a metallic equivalent. So apart from the differences that there may be between the radicals R, R1, R2 of the amino acids of the US patent and the groups R, R 'according to the present invention, a fundamental difference resides in that the hydrocarbon substituent R1 of the US patent is attached to nitrogen, while the group R, according to the invention, is linked to a tertiary carbon atom; in fact the latter carries three different substituent groups (N-, R and -COOM) next to a hydrogen atom. That this structural difference could have brought microemulsifying properties to the molecule if

pronounced, is a completely unexpected new development.

  This first Addition also includes a new feature with regard to the optimal salinity of the water subjected to the emulsion or microemulsion. While,

  in the examples of the main patent we did not exceed the t-

200 g of NaCl per liter of water emulsified with hydro-

carbide, the present invention achieves 280 g / l.

The most judicious choice of the operating conditions, according to the invention, appears from the numerical data, indicated below. Among these data are results obtained with the sodium salt of Nacetyl α-amino acid of which the group R

  has 22 carbon atoms, which gives great results.

  It should be noted in this connection that a long chain R may consist of an oligomer group of an olefin, in particular of polyethylene, polypropylene, polybutylene or polyisobutylene;

such a chain can count for example 4 to 40 mono-o- units

  lefiniques, which represents, in the case of propylene, 12 to

  carbon atoms. Thus R can be branched or alkyl-aryl.

Thus, for carrying out the present invention, the N-acylamino acid salts employed preferably carry an R group at C16 to C120, and better still at 022 to C60. The R up

C32 were provided for in the main patent, but the perfection-

  According to this 1st Addition, resides in the possible use of surfactants in which the group R contains 33 to 120 carbon atoms and, more especially, 33 to 60 C.

The results of the Tables which follow were obtained

  kept by mixing at 30 C, with slight stirring, of: 47 volumes of salt water, the NaCl content of which is indicated for each test; 47 volumes of a specific hydrocarbon; 3 volumes of alcohol: 2 vol. of butanol2 and 1 vol. of 3-methyl-butanol -1

3 g (= 3 vol.) Of a surfactant, Na salt of N-

  acetyl a-amino acid: CH3CONH-CH-COONa

AT

  o R is normal alkyl, the number of a-

  volumes of C is specified in the tables.

TABLE I

Optimal water salinity. in q NaCl / liter.

  Hydrocarbon s Octane Decane Dodecane R of the NaCI surfactant q / l

C12 220 250 280

C14 180 210 240

C16 110 135 165

C22 50 60 80

  We see that with dodecane, the R of the surfactant being the lau-

  ryle, it is possible to work with water at 280 g NaCl / liter. Table I also shows that a surfactant with R at C22 is compatible only with lower salinities, from 50 to 80 NaCl g / l, but, on the other hand, it appears from Table II that then

  we arrive at a maximum solubilization parameter.

The solubilization parameter is the volume of water

  or solubilized hydrocarbon per unit volume of ten-

sioactive, in the middle phase of the microemulsion, for optimal salinity. In the present trials, since there are 47

  volumes of hydrocarbon and as much salt water, for 3 vol. from a-

  gent surfactant, the maximum solubilization parameter is 47: 3 = 15, 66; for this value the whole system forms one

emulsion phase.

TABLE II

  Solubilization parameter: Hydrocarbon: R of the surfactant Octane Decane Dodecane

12 5.5 4.0 3.5

14 11.0 7.5 6.0

16 15.5 15.5 11

22 15.5 15.5 15.5

The advantage of using long-chained surfactants stands out

  of these results, since with an R in C16 octane and de-

  cane are fully microemulsified, and with C22 all

  three hydrocarbons are (value of 15.5).

  These results are all the more remarkable since the environment

holds only 3% surfactant versus more than 5% and

  usually even 10 to 15% required in the known technique

microemulsions. -

The nature of the alcohols, or other co-agents, influences - as is known on the emulsion results; so are

even for the present invention.

  It is also known that temperature plays a role which can result in the inversion of an emulsion or a microemulsion. Tables III and IV, below, show that the new surfactants according to the invention are

  not very sensitive to variations in temperature.

TABLE III

Optimal water salinity, in g NaCl / Liter, at different temperatures. Octane Decane Dodecane Hydrocarbon

R 30CC 60C 85 C 3 085

12 ........ 220 200 210 250 240 240 280 255 255

  14 ........ 180 170 165 210 200 195 240 220 220

  16 ........ 110 115 110 135 125 120 165 145 150

22 ........ 50 45 40 60 55 55 80 75 70

There is a slight decrease in optimal salinity, when

  as the temperature rises, but - often - the differences are of the order of measurement errors (+ 10 g / l)

TABLE IV

Solubilization parameters according to Octane Decane Hydrocarbon

 C 600C 85 C 30 C 60 C 850C

of the temperature.

Dodecane 300C 60eC 85C '

R

12 ...... 5.5 4.5 3.0 4.0 3.0 3.0 3.5 3.0 2.5

  14 ..... 11.0 8.5 7.0 7.5 6.5 5.0 6.0 5.0 4.5

16 ...... 15.5 15.5 11.5 15.5 11.0 8.0 11.0 9.0 7.0

  22 ...... 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5 15.5

  The important result of this table is that with surfactants

  active according to the invention, neither the temperature nor the molar mass

of the hydrocarbon no longer prevent obtaining a

single emulsion phase (parameter 15.5), if the radical R

closes more than 16 carbon atoms.

  The Na salt of N-acetyl α-amino acid of which R is C22, i.e. sodium N-acetyl α-amino tetracosanoate, was applied to the preparation of crude petroleum microemulsions with l 'salt water. We tried two crude samples

  American, one from EXXXON and one from the STORMS POOL deposit (Illi-

  nois), each with two W / O ratios (water / hydrocarbon), 1 and 2. We operated at 450C with only 3% of surfactant and 3% of

alcohols (2% isoamyl alcohol + 1% butanol-2).

  Table V contains the results.

TABLE V

  Optimal salinity g NaCl / l Parameter of

solubili-

  gross station of EXXXON: (API degree: 38; viscosity: 6 cp)

W / O = 1 60 - 80 15.5

W / H = 2 60 15.5

  Gross STOPRMS POOL: (API degree: 35; viscosity 5.8 cp)

W / O = 1 75 15.5

W / H = 2 60 15.5

  In all cases, a single microemulsion phase was obtained.

outfit.

  Similar results are obtained with potassium, ammonium or propylamine salts of the N-acyl α-amino acids used above. The same is true with the following surfactants: sodium N-propionyl aamino hexadecanoate, magnesium N-butyryl a-amino hexadecanoate, ammonium N-propionyl a-amino eicosanoate, N-butyryl a-amino triacontanoate potassium, CH3CONH-CH-COONa of which the group R is an oligomer of propylene Rene from approximately 20 units CH3CH- = CH2

TABLE VI

  Optimal water salinities, in q NaCl / liter, for surfactants whose R groups are branched R branched from the Hydrocarbon: Octane Decane Dodecane surfactant

C12 210 235 265

C14 170 200 225

C16 105 120 150

C22 40 55 70

  Although the optimal salinities are a little lower for iso- (branched) compounds, compared to those of Table I, these branched agents are very suitable, do not tend to gel and give parameters of

high solubilization.

  Note: During this description the expression "Salinity

  optimal "designates the% by weight of NaCl for which the interfacial tension between the hydrocarbon and

the water is the weakest.

Claims (9)

1. Process for the preparation of emulsions and microemulsions by mixing water with a water-immiscible liquid,   especially a hydrocarbon, in the presence of a surfactant active ingredient consisting of an N-acyl α-amino acid salt; of the type Rt -CONH-CHCOOM R o R and Rt are aliphatic groups, M being a cation,   characterized in that the proportion of this agent is lower   less than 5% of the weight of the mixture to be emulsified. 2. Process for the preparation of a microemulsion, according to the   vendication 1, characterized in that the proportion of agent   surfactant is between about 0.5 and 5% by weight.   3. Method according to claim 1 or 2, characterized in that   that the water used contains 200 to 280 g of NaCl per liter.   4. Method according to one of claims 1 to 3, characterized   in that the group R of the surfactant employed is in   C33 to C120 and, more specifically, in C33 to C60.   5. Application of N-acyl α-amino acid salts of the type   R'-CONH-CH-COOM with assisted oil recovery, charac-   R terized in that it is carried out by the process according to a of claims 1 to 4.   6. Surfactant, particularly useful for the preparation of aqueous microemulsions, consisting of an alkali or alkaline earth metal, ammonium or amine salt, of a   N-acyl a-amino acid defined in claim 1, character-   laughed at in that its R group contains 33 to 120 carbon atoms bone, and more specifically 33 to 60.   7. Agent according to claim 6, characterized in that the   group R is an olefin oligomer. 8. Agent according to claim 7, characterized in that the o   ligomer is that of ethylene, propylene, butylene or isobutylene, and that it is formed from 4 to 40 mono-ole units finiques. 9. Agent according to claim 6, characterized in that the group R is an alkyl aryl.